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About Hand

by Jon Trister MD

Carpal arch

Carpal arch consists of carpal bones ant transverse carpal ligament (TCL). TCL attached to scaphoid and trapezium radially and the pisiform and hamate ulnarly. There are several muscles are known to originate from the TCL. Hypothenar Group:

Opponent digital minimi

Origin: convexity of the Hamulus of the hamate bone and the contiguous portion of the transverse carpal ligament;

Insertion: into the whole length of the metacarpal bone of the little finger, along its ulnar margin

Abductor digiti minimi muscle of hand

Origin: Pisiform bone, the pisohamate ligament, and the flexor retinaculum

Insertion. Base of the proximal phalanx of the 5th digit on the ulnar or medial side

Flexor digital minimi.

Origin: Pisiform bone, the pisiohamate ligament, and the flexor retinaculum

Insertion: Base of the proximal phalanx of the 5th digit on the ulnar or medial side

Thenar Group:

Flexor pollicis brevis:

Origin: Ridge of the trapezium and TCL

Insertion: Base of the Proximal phalanx of the thumb and Extensor expansion.

Opponent pollicis:

Origin: trapezium and transverse carpal ligament

Insertion: metacarpal bone of the thumb on its radial side

Abductor pollicis:

Origin: Transverse carpal ligament, the scaphoid and trapezium

Insertion: Radial base of proximal phalanx of thumb and the thumb extensors.

Some anatomy texts consider TCL as a middle portion of the Flexor Retinaculum (FR), other describe it as separate structure based on their functions which are quite different: FR performs predominantly proprioceptive and TCL stabilizing roles

Tensions generated by TCL together with interosseous carpal ligaments determine form, length, width, of the carpal tunnel. Content of the carpal tunnel and its relationship to the  structure which form carpal tunnel will determine its  function.

Form of the carpal tunnel is not static, but dynamic and changes depending on the tasks performed by writs, hands and fingers.

There is a wrist retinaculum (FR) which perceive, analyze and communicate locally (local reflexes, mechanoreceptors)  and centrally (CNS) to coordinate optimal function of the wrist and fingers.

Form, direction , length and width of the carpal tunnel is constantly  changing depending on the tasks performed by the fingers and hand and adapt morphologically  to optimize these functions.

Several muscles control TCL and subsequently carpal tunnel: Thenar, Hypothenar, interossei, lumbricalis, Flexor carpi ulnaris, Palmaris longus, palmar aponeurosis.

Local connective tissue also participates in this process utilizing forces of elasticity.

Information from distal parts of the hand ( MCP, PIJ,DIJ, A pulley, C pulley, joint’s capsule, synovium) reciprocally transmitted (communicates) with proximal structures as well: TCL, carpal joints and its capsules, distal pronators qadratus.

All together creates anatomo-functional unity for coordinated activity of the hand.

The carpal canal consists of a variety of morphological tissues: ligaments, muscles, bones, cartilage, vasculature and nerves.  The contents of the carpal canal are also diverse: within it we find tendons, muscles, arteries and nerves which secure the normal function of these structures within and outside carpal tunnel. The function of the structures located within the carpal canal depends on the volume, form, ductility, plasticity and elasticity of the structures that make up the carpal canal. Volumes and forms of the carpal tunnel are dynamic and not static. The form and volume of the carpal tunnel are constantly changing reflecting function of the arm, hand, fingers performed at particular time (at each functional moment).

Various functions (actions) of the arm, hand and  fingers will influence the function of the direction of forces and mechanical stress of the structures passing through the canal; gravitational forces play an important role in the generation of the mechanical  stress on the carpal tunnel and its contents which has a clinical correlation especially as the elastic properties of the structures forming the carpal canal lose elasticity, become more plastic and cannot resist forces of gravity.

When vectors of gravitational forces change allowing restoration of their original form, the carpal tunnel symptoms of numbness, heaviness and dysfunction improve.

Hand instability may have various presentations.

There are many different manifestations of this process: Osteoarthritis, Enthesopathies, Neuropathies, Contractures, Deformities. All of these pathologies will be always present in various degrees.

The choice of therapy depends on degree of the damage, location of the predominant symptom, previous injuries, age of the patient, duration of the symptoms, previous treatments, and presence of other medical problems.

Clinical presentation never comes from one source.

Pain and instability of the scapho-trapezium-metacarpal complex associated with laxity of the transverse wrist ligament, laxity of the flexor and extensor retinaculum, weakness of the thenar and hypothenar muscles, palmaris longus.

Ligaments which connect carpal bones could be lax. This will preclude them from keepIng a normal arch of the palm.

Strength of the transverse ligament, elasticity of the inter-carpal ligaments, thenar and hypothenar strength and forms of the carpal bones will determine the volume of the carpal tunnel, interaction of the structures inside the tunnel, direction of the movement of the bones.

Transverse ligament attached to the scaphoid and trapezius on the radial side and to pisiform and hamate on the ulnar side. This anatomical connection controls stability of the scapho-trapezium-metacarpal joints and ulnar aspect of the hand. Palmar aponeurosis has direct connection to palmaris longus; and flexor carpi ulnaris controls transverse ligament attachment on the ulnar side.

Flexor and extensor retinaculum provide proprioceptive information to all these structures assuring coordinating activity. Stability of the distal RU junction controlled by dorsal and palmar ligaments , TFCC, pronator quadratus  and interosseous membrane; 

The proximal RU junction is controlled by annular ligament, it’s tension will be controlled by the action of the Biceps and pronator teres.

Thumb pain.

Treatment Prolotherapy. 15-20 cc 15 % dextrose.

Use 27 G needles. Target structures: 

Medial humeral epicondyle-flexor carpi ulnaris and pronator teres

Lateral elbow: If annular RU ligament is painful ( proximal RU junction);

Styloid process of the distal radius and dorsal aspect of the radius; Distal RU junction; TFCC; Entire capsule of the carpal joint on the posterior aspect.

Carpal ligaments: they keep the arch; Pisiform, Hamate, Base of the 5-th MC bone.

Then , scapho-trapezium-metacarpal joints: anterior , lateral and  posterior aspects

Consider scapho-lunate and luno-triquetral joints; 

Inject around capitate bone as well.

MCP joint and IPJ.

Carpal tunnel:

Treatment Prolotherapy. 15-20 cc 15 % dextrose.

Use 25-27 G needles. 

Target structures: 

Medial humeral epicondyle-flexor carpi ulnaris and pronator teres

Lateral elbow: If annular RU ligament is painful ( proximal RU junction);

Styloid process of the distal radius and dorsal aspect of the radius; Distal RU junction; TFCC; Entire capsule of the carpal joint on the posterior aspect.

Carpal ligaments; Pisiform, Hamate, Base of the 5-th MC bone.

Then, scapho-trapezium-metacarpal joints: anterior, lateral and  posterior aspects

Scapho-lunate and luno-triquetral joints; 

Transverse metacarpal ligaments and MCP joints

Inject around capitate bone because of many ligaments connect this bone with other carpal bones.